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Houseplant pests, part 2

Previously I shared the bad news that houseplant pests are inevitable. But the good news is they can be treated. In the previous post, I also told you about public enemy number 1: spider mites. In this post I'll tell you about three other common houseplant pests.

These are white, fluffy bugs that leave a white powdery residue. They like to hide in the crevices of the plant. You can pull back the petiole and they will be between the petiole and the stem. It may be necessary to pull the petiole back far enough that it damages the leaf in order to identify them. Mealy bugs cause leaves to turn yellow. They will eventually kill the plant.

Byron, M. A., & Gillett-Kaufman, J. L. (2019, September). longtailed mealybug, Pseudococcus longispinus. Featured Creatures. Retrieved May 30, 2022, from

I use a combination of a systemic treatment (Bonide systemic granules) and horticultural oil. You need to make sure to spray the front and back of the leaves with horticultural oil, and in all the crevices of the plant. Spray weekly for prevention.

These are tiny, slender bugs that can be seen on the top and bottom of the leaf. If the plant flowers, you may see them within the petals. The adults are dark brown and the young thrips are clearish. They lay their eggs in the soil. Thrips fly so if you encounter them you will need to keep an eye out for them on the rest of your plants as well.

Denmark, H. A. (2019, February). greenhouse thrips, Heliothrips haemorrhoidalis. Greenhouse Thrips - Heliothrips haemorrhoidalis (bouché). Retrieved May 30, 2022, from

Thrips cause silvery, brown spots on the leaf and will eventually kill the plant.

Thrips are hard to eliminate without a systemic treatment. I use a combination of bonide systemic granules and horticultural oil. Make sure to spray the top and bottom of leaves. Also spray all the other plants that you have in the same room. Spray weekly for precautionary measures.

Fungus gnats

These are tiny black bugs that fly around your plant. They are not harmful to your plant; they are just a nuisance. They lay their larvae, which appear as tiny, white worms, in the soil. You will need to treat these with two different things. First, you can sprinkle mosquito bits on the top of the soil, which you should then water in well. Let your plant dry out between waterings. This will ensure that they won’t come back. Secondly, put yellow sticky traps around your plants. The adult fungus gnats are attracted to the yellow color. This will catch all the adults.

Mead, F. W., & Fasulo, T. R. (2017, December). darkwinged fungus gnats - Bradysia spp. Darkwinged fungus gnats - bradysia spp.. Retrieved May 30, 2022, from

This sticky trap has caught some houseflies, mosquitos, and fungus gnats. The fungus gnats are the smallest insects on the sticky trap.

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